We propose to use high field 2H NMR spectroscopy to characterize molecular ordering, in-plane interactions, and motions of choline-containing phospholipids in normal intact nerve, isolate myelin and myelin lipid extracts. For this purpose we will biosynthetically label neural membranes from mammalian central and peripheral nervous systems with deuterated choline, thus providing an intrinsic non-perturbing probe which can be monitored in the intact membrane. We will investigate the interactions with myelin of physiologically (Ca 2 ion, Mg 2 ion) and pharmacologically (local anesthetics) significant agents and of other chemical aagents (dimethylsulfoxide, triethyltin) known to alter myelin morphology in vitro. To enable interpretation of intact membrane experiments we will concurrently study complex model bilayer systems composed of synthetic deuterated phospholipids and various myelin phospholipids and sphingolipids, in addition to systems containing specifically deuterated sphingomyelin. Information relating to the ordering and motions of the deuterated components in both intact membranes and model systems will be obtained from the temperature dependence of deuterium quadrupole splittings, line shapes and spectral intensities.